This invention relates to an automatic dishwasher detergent composition. Dishwasher detergent compositions generally contain alkaline builder salts including sodium silicate for its china protection ability, a chlorine bleach for the purpose of breaking up food particles into more soluble forms, and a water-soluble synethetic organic detergent for its cleaning and water-sheeting ability. Preferably such detergent compositions should be formulated with a relatively high alkaline pH in excess of about 8.5.
The alkaline builder salts are usually employed as a major component of the composition. This ingredient is the primary cleaning component and additionally may desirably possess the ability to sequester hardness imparting ions found in water. Although it may be possible to formulate detergent compositions without a sequestering builder salt, it is highly preferred to have a sequestering builder salt present.
Despite the excellent detergency benefits found in conventional automatic dishwasher detergent compositions, it is usually necessary to prepare dishes for the automatic dishwasher by scraping off some soils which adhere tightly to the dishes. Thus there has been a clear need for automatic dishwasher compositions either with improved cleaning ability or which incorporate a soil-release agent to permit the more ready removal of such tightly adhering soils.
Phosphorus-containing materials have been suggested for use as soil-release agents in dishwashing compositions and in machine dishwasher rinse aids. U.S. Pat. No. 3,941,713, Dawson et al (Mar. 2, 1976), discloses a rinse composition for machine dishwashing containing an organic phosphate.
Similar disclosures relating to dishwashing in general, and especially to dishwashing compositions containing organic phosphate and/or phosphate soil-release agents, can be found in South African patent application No. 72/03559 (corresponds to Netherlands patent application No. 7207017 and Canadian Pat. No. 969,832); British Pat. No. 1,395,031 (May 21, 1975); British Pat. No. 1,315,636 (May 2, 1973); U.S. Pat. No. 3,956,199, Dawson et al (May 11, 1976) and U.S. Pat. No. 3,963,635, Dawson et al (June 15, 1976).
Another disclosure of an organic phosphonate in an automatic dishwashing composition can be found in Belgian Pat. No. 819,982 (Mar. 17, 1975) and dishwashing with an aryl-polyoxyethylene phosphate is disclosed in U.S. Pat. No. 3,032,578, MacMullen et al (May 1, 1962).
The use of organic phosphates and phosphonates in detergent compositions in general is well known as can be seen from e.g., U.S. Pat. No. 3,294,693 (use as a hydrotrope); U.S. Pat. No. 3,957,661 (fabric softening); Belgian Pat. No. 802,004 (fabric softening); Belgian Pat. No. 835,803 (cosurfactant); German patent application No. 2,537,570 (foam suppressant); U.S. Pat. No. 3,869,412 (foam suppressant); Dutch patent application No. 73/04706; and U.S. Pat. No. 3,351,558 (corrosion inhibitor). All of these patents and applications are incorporated herein by reference.
Despite the many disclosures of the use of phosphours-containing surfactants in detergent compositions, especially dishwashing compositions, and more precisely, automatic dishwashing compositions, and the disclosure of the soil-release benefits which can be derived from using phosphorus-containing surfactants in dishwashing compositions, it has not been possible heretofore to formulate an automatic dishwashing composition having a pH &gt;8.5 containing long chain random alkyl phosphonates as soil-release agents. The problem arises primarily from the presence of hardness ions in the water. Despite the presence of large amounts of sequestering builders the long chain alkyl phosphonates react with the hardness ions present to form an insoluble deposit which is very unsightly.